// #docregion
var gifts = {
// Keys      Values
  'first': 'partridge',
  'second': 'turtledoves',
  'fifth': 'golden rings'
};

var nobleGases = {
// Keys  Values
  2: 'helium',
  10: 'neon',
  18: 'argon',
};
// #enddocregion

void main() {
  // #docregion const
  final constantMap = const {
    2: 'helium',
    10: 'neon',
    18: 'argon',
  };

  // constantMap[2] = 'Helium'; // Uncommenting this causes an error.
  // #enddocregion const

  nobleGases[2] = 'Helium'; // You can do this.
  try {
    constantMap[2] = 'Helium'; // You can't do this.
  } catch (e) {
    print('Tsk tsk! $e');
  }
}

//36: 'krypton',
//54: 'xenon',
//86: 'radon',
